Fix non-termination

The non-termination is caused by typo in the level of `Outer`:
it should be `pot.level` instead of `pot.size`.

Author: liufengyun

compiler/src/dotty/tools/dotc/transform/init/Checking.scala

@@ -227,7 +227,7 @@ object Checking {
       val cls = denot.symbol.asClass
       val potInner =
         pot match
-        case warm: Warm => Warm(cls, pot)(source)
+        case warm: Warm => Potentials.asSeenFrom(Warm(cls, ThisRef()(source))(source), pot)
         case _ => LocalHot(cls)(source)
       buffer += MethodCall(potInner, cls.primaryConstructor)(source)
       buffer += Promote(potInner)(source)

compiler/src/dotty/tools/dotc/transform/init/Potentials.scala

@@ -116,7 +116,7 @@ object Potentials {
   case class Outer(pot: Potential, classSymbol: ClassSymbol)(val source: Tree) extends Potential {
     // be lenient with size of outer selection, no worry for non-termination
     override def size: Int = pot.size
-    override def level: Int = pot.size
+    override def level: Int = pot.level
     def show(using Context): String = pot.show + ".outer[" + classSymbol.show + "]"
   }
 
@@ -125,7 +125,7 @@ object Potentials {
     assert(field != NoSymbol)
 
     override def size: Int = potential.size + 1
-    override def level: Int = potential.size
+    override def level: Int = potential.level
     def show(using Context): String = potential.show + "." + field.name.show
   }
 
@@ -134,7 +134,7 @@ object Potentials {
     assert(method != NoSymbol)
 
     override def size: Int = potential.size + 1
-    override def level: Int = potential.size
+    override def level: Int = potential.level
     def show(using Context): String = potential.show + "." + method.name.show
   }
 
@@ -224,13 +224,11 @@ object Potentials {
 
       case Warm(cls, outer2) =>
         // widening to terminate
-        val thisValue2 = thisValue match {
-          case Warm(cls, outer) if outer.level > 2 =>
-            Warm(cls, Cold()(outer2.source))(thisValue.source)
-
-          case _  =>
+        val thisValue2 =
+          if thisValue.level + outer2.level > 4 then
+            Cold()(outer2.source)
+          else
             thisValue
-        }
 
         val outer3 = asSeenFrom(outer2, thisValue2)
         Warm(cls, outer3)(pot.source)

tests/init/neg/inner-loop.scala

@@ -1,6 +1,6 @@
 class Outer { outer =>
   class Inner extends Outer {
-    val x = 5 + outer.n
+    val x = 5 + outer.n       // error
   }
   val inner = new Inner
   val n = 6               // error